Flashtube triggering circuits



y 3, 1950 H. w. LORD 2,509,005

FLASHTUBE TRIGGERING CIRCUITS Filed Oct. 17, 1949 2 Sheets-Sheet l I8SATURABLE.

l7 6 LrLfL 5 4 28 J 29 a 27 O 57 2! 20 a Lrui A.C.

SOURCE Inventor: Harold W. Lord,

H is Attorney.

2 Sheets-Sheet 2 Filed 001;. 17, 1949 Fig.5. 56

WSATURABL;

Fig.4.

SATURABLE Inventor Haw-old W. Lord, by 49$ 4. 7'

H is Attorney.

Patented May 23, 1950 UNITED STATES PATENT OFFICE FIIA'SHTUBE TRIGGERINGCIRCUITS Haroid W. Lord, Schenectady, N. Y., assignor-to GeneralvElectric Company, a corporation of New York My invention relates tofiashtube' triggering circuits and-is-a continuation in part-of mycopending application; SerialNumber 703,059; filed October 12, 1-946}now-aba-ndoned.-

Discharge devices=of thecold cathode-gasor mercury vapor type comonlyknown-inthe art as flashtubes have come into generaluse'particularly inphotographic and: stroboscopic alpplicationsmainlybecause'of 'theirability. to emit high intensity illumination and to reach full intensityalmostinstantaneously. usually desirable that the-devicefurnishilluinination only during very -shor-t increments oitime and tofurnish sucha flash at any chosen instant and at any chosenrepetitionrate.

Such a-device'usuallycomprises an-anode and cathode asthe mainelectrodes within a gastight glass enclosure in which-a smallquantity ofgas or mercury in liquidfor vapor form-isplaced. A- metallictriggeringelectrode, commonly arranged in contact withthat portion oftheouter surface of the glassenclosu-re nearthe cold cathode, maya-lsdbe-provided; Electrical discharge does not occur whennormalanode-to-cathode voltage is" applied, since'ionization remainssufliciently low to prevent' breakdown through the enclosed gas.However; ionizationtmay be increased sufficiently to cause discharge bysharply increasing the voltage-gradient in-the gas or a portion thereof.Sucha; voltage gradient increase causes increased ionizationsincedisplacement current or condenser charging current-in the dielectricconsisting of the enclosed.- gas results; which current causes aditionalionization. This maybe accomplished 'by applying avoltage pulse betweenanode and cathode, or between triggering electrode and cathode. 'lherequired amplitude of the voltage pulse is less if a-triggeringelectrode is employed;

Such discharge continues as long as the anodeto-cathodevoltageexceedsacritical value below which current flow stops. Thus asource of anode-to-cathode voltage capable of supplying energy andof'sharply: dropping load characteristic must be provided if fiashesof-short duration are desired. Further; a large triggering voltage mustbesuppliedat theinstant illumination is desired.-

Where a plurality of flashtubes are to be simultaneously dischargedit isdesirable that the triggering current should notbeincreased beyond amagnitude which relativelyz small circuit making and breaking contacts,such as shutter contacts on a camera, may safely handlewith outadditional rela'ying components.- At-'- the Also, it is same time, it isdesirable toemploy a relatively simple controlcircuit as for singleflashtube operation without employing duplicate triggering or relaycircuits for the additional fiashtubes.

It is an object of my invention to provide a new and improved circuitwhich supplies reliable and adequate triggering voltage andadequateenergy to the main discharge.

It is another object ofmy invention to-provide a new and improvedcircuit for a cold cathodegas or mercury vapor luminescent dischargedevice which is simple and compact and supplies all requirements of-thedevice.

It is another obj ect' of my inventionto provide an improved triggeringcircuit for multiple flashtube operation.

lt is a further object-of myinvention to providea fiashtube circuitarrangement for triggering of one or more slave flashtubes inresponse tothe triggering of a first fiashtube.

Aecordingto my invention, I- employ in a-circult for producing light byadirect current discharge through one or more flashtubes, a saturable'core inductance-device connected inseries 5 between the direct currentsource and the flashpended claims.

tube load, together with" a; switching arrangementfor suddenl impressinga part or allof the voltage of thesource across the inductance device.Due to the initially high permeability of the inductance devicecore,very littlecurrent fiowsthrough the inductance device after the voltageis impressed untilthe core saturates, thus terminating the voltagepulse. This voltage pulseisemployedto trigger one or more flashtubes,the: inductancedevice being so designeddrawings inwhich Fig. 1represents a'fiashtubetriggering and supply c-ircuitembodying myinvention, and Figs. 2-. 3, and-a5 are modiiicm tions.

Referring now to Fig. 1, a triggering anden' erizingcircuit is shownwhich may be energized from-an A; C. source through the primary oftransformer The usual switch 2 is provided in the primar circuit of tiSfOlZ'liSl" i 1201' energization or deenergization o the circuit. Avoltage doubler rectifying circuit. supp-lied by the secondary 3 or"transformer 5, consists in part of condenser rectifier d, isolatingresistor E, and condenser 53 connected in series across secondary 3='iwith the rectifier E5 allowing current flow in the same direction as theorder in which the elements are enumerated. Another rectifier 9 isconnected across the serially connected secondary 3-& and condenser {orcurrent flow through rectifier Q from terminal of secondary 3& towardsthe junction between condenser 5 and rectifier 6.

When energized, terminal 3 becomes positive with respect to terminalduring one-half of each cycle of A. C. voltage. During this timerectifier 9 becomes conductive and charges condenser 5 and rectifier 5remains nonconductive. During the next half cycle terminal t becomespositive with respect to terminal 3 and rectifier 6 becomes conductiveand essentially double the voltage of secondary 35 is impressed acrossthe resistance 7? condenser ii in series. Thus, condenser 53 becomescharged to a voltage double the maximum instantaneous voltage ofsecondary 3- 3 ii an A. C. voltage is on transformer l for a time notless than a minimum time dependent upon the values resistance l andcondenser 8.

The voltage of condenser S is made available across a series circuitconsisting of primary it of a saturable core transformer ll, condenser ii shunted by resistance l5, and a normally open switching device such asthe normally nonconducting gaseous discharge tube it connected acrosscondenser 8 with the cathode H of tube Ill connected to the negativelycharged plate of condenser 23. Anode i2 of tube Iii is connected to oneterminal of condenser l4. Control grid !3 of tube ill is held at zeronormal bias voltage by resistor 59 connected from cathode H to grid 13.Resistor it is also part of a circuit consisting of condenser 29,isolating resistor 2|, and rectifier 22 connected in series acrossportion 23 of secondary 3- 1 of transformer l. Rectifier 22 is connectedto allow current flow when ter minal 3 is positive with respect toterminal 4 of secondary S- l, thereby allowing condenser 28 to becomecharged to the maximum instantaneous voltage of coil 23 with itspositive terminal connected to the junction of grid :13 and resistor l9.Condenser 2B and resistor 19 in series are shunted by a discharge keyingdevice 24, the purpose of which will be explained. The cathode heater oftube It) may be supplied from the secondary coil 25 of transformer I.

A space discharge tube 26, such as is commonly known in the art as aflashtube, having a cold cathode 2i, anode 28 and triggering electrode29 is employed as the controlled source of illumination. The voltage ofcondenser 8 is made available to tube 26 by connecting cathode El to oneside of condenser 8 and anode 28 to the other side of condenser 3, thelatter connection being made through the secondary winding 58 oftransformer H. The trigger electrode 29 is connected to anode 28 througha resistance 39. Resistor 38 is employed to prevent sustained arcingbetween cathode and trigger electrode over the exterior surface of thetube, if such arc is initiated by any cause.

When the circuit is energized and key 2 1 is left open, tube l0 and tube26 are both nonconducting. Condenser 8 is charged to a voltage equal totwice the maximum instantaneous voltage of secondary coil 34 oftransformer i, as previously described. Condenser 20 is charged to avoltage equal to the maximum instantaneous voltage of secondary coil 23of transformer i with the plate connected to grid 13 positively charged.Grid i3 is at a negative potential with respect to cathode ll of tubeIll as caused by voltage drop in resistor l9 while condenser 26 is beingcharged and arrives at zero potential when condenser 23 is fullycharged. Tube I0 is of a type which requires a positive grid voltage toinitiate a discharge through it. It has preferably a voltage rating inexcess of the desired voltage charge on condenser 8, thereby preventingthe possibility of loss of grid control at zero bias.

The anode to cathode Voltage on tube it is normally the full voltage ofcondenser 53 since no current is flowing in primary l8 of transformer iiand condenser i4 is uncharged. The anode to cathode voltage of tube 26is also equal to the full voltage of condenser 8 since there is neitherinduced voltage in nor current through secondary it of transformer l1.Further, electrode is at anode potential since there is no current inresistor 38.

Actuation of key 24 drives grid it of tube l'l positively to a voltageequal to that of condenser 25 and initiates a discharge from cathode iito anode i2. Resistor 2| prevents shorting of secondary 23 oftransformer I while key 24 is depressed. It may be preferable to employa low EC time constant in the circuit consisting of condenser 28 andresistor 19 in series to insure return of grid i3 to control statusimmediately after tube ill again becomes nonconducting. It is apparentthat grid I3 may be controlled by other means such as an amplifier orelectronic switching means without departing from the principles of myinvention.

When tube it becomes conductive, a voltage appears across primary 16 oftransformer ii to an amount les than condenser 3 voltage by thecathode-anode voltage of tube it) necessary to sustain tube currentflow. Current then builds up in primary H3 and condenser l4 charges up.When insufficient voltage remains across tube iii to sustain currentflow through it tube returns to a nonconducting status, causing currentflow through it and through the primary iii to cease. Condenser M thenreturns to normal zero charge by discharging through the shuntingresistor 15. Therefore, condenser l4 shunted by resistor constitutesautomatic resetting means responsive to integrated current flow forcausing the S WitCh" ing device [H to return to its normally opencircuit condition.

When a D. C. voltage is suddenly applied across primary l6 as by causingtube ID to become conductive, a similar voltage appears across secondaryES whose magnitude bears the same ratio to the primary voltage as theturn ratio of transformer El. This secondary voltage adds to the voltageof condenser 8 to cause a sudden increase of voltage gradient withintube 26, thereby cans ing tube 2 5 to become conductive.

When tube 28 become conductive, the voltage across tube 26 suddenlydecreases to a value just sufficient to maintain discharge through it.Thus the voltage across secondary I8 must necessarily change indirection and amount at the instant tube 28 becomes conductive. Thisvoltage change may be considered as an induced voltage in secondary l8caused by the initiation of current flow through it as required by tube26. As the current flow to tube 25 increases, an induced voltage remainsto an extentdependent upon the rate of chan e of .flux linkingsecondaryl8, which in turn is complexly dependent upon current and theinstantaneous reluctance of the magnetic circuit linking secondary I8.When tube 26 becomes fully conductive the magnetic circuit oftransformer i1 is saturated as stated previously, the induced voltage ofsecondary I8 is consequently decreased to a small value, and secondary[8 may then be considered as a saturated reactor essentially decoupledfrom primary l6 and of relatively low inductance value. Energy is,therefore, supplied to tube 26 from condenser E at a voltage somewhatless than the decreasing voltage of condenser 8. Discharge of condenser3 decrease its voltage and when this voltage becomes insufiicient tosustain discharge through tube 26, tube 26 again becomes nonconducting.Isolating resistor l prevents undue current flow in secondary 3-4 whiletube H] and tube 23 are conductive.

The inductive efiect of secondary I8 may tend to prolong the dischargetime of tube 26 since a current decrease through it in the range ofcurrent values below saturation current induces a voltage in secondaryI8 by self induction of additive polarity with respect to the voltage ofcondenser 8. This may be compensated by using a smaller capacity forcondenser 8 which will cause a more rapid decrease in voltage acrosscondenser 8 when tube 26 is conducting. However, a higher voltage chargeon condenser 8 should then be employed if the total energyavailable forillumination is to be the same.

The sequence described above may be repeated at any repetition ratewhich will allow sufficient time for recovery of proper charges oncondensers 3 and 26 before the next discharge sequence occurs.

As shown in Fig. 2 a modification of a flashtube triggering circuitembodying my invention is employed to trigger a second or slav flashtubefrom the operation of a first or master flashtube. Accordingly, circuitterminals 3! and 32 are connected to the positive and negativeterminals, respectively, of a direct current voltage source toappropriately charge a condenser 33 A resistor 34 is preferablyconnected in series between the condenser 33 and the voltage source toregulate the condenser charging rate as desired. A saturable coretransformer 35, arranged similarly to the transformer I! in Fig. 1, hasits common connection for one end of the primary winding 33 and one endof the secondary winding 3'! connected to the positively charged plateof the condenser 33. A gaseous discharge device or fiashtube 38 designedto emit light upon the passage of a substantial current between .itsanode 39 and cathode at is connected in circuit with its anode connectedto the other ,endof the primary winding .36 and its cathode connected tothe negative- 1y charged plate of condenser 33. The fiashtube 38 has atriggering electrode 4| and is preferably of a type arranged to betriggered by a relatively low power pulse applied between its triggeringelectrode 4i and cathode 53 so that no gaseous discharge tube need beemployed in its triggering circuit. A satisfactory voltage source forthe triggering pulse may be suitably provided by connecting voltagedivider resistors 42 and A3 in series across the plates of the condenser33. The primary winding of a triggering transformer 44 is connected tothe negative plate of the .con-

denser 33 and to the common connection of the voltage divider resistors42 and 43 through a triggering condenser 45, and the secondary -wind-.ing of the triggering transformer 44 is connected between the triggeringelectrode 4,! and the oath-.- ode of the flashtube. The triggeringimpulse is provided by closing a switch 45 which is shunted across thevoltage divider resistor 43, thereby impressing the full voltage of thecondenser 33 across the series connected triggering condenser andprimary winding of the triggering transformer 44. The resultant surge ofvoltage across the transformer primary is suitably multiplied in itssecondary winding by the transformer turns ratio to breakdown thefiashtube .38 and initiate current flow between its main electrodes. Theswitch l'ii may be, for example, the contacts on the shutter mechanismof a camera, when the apparatus is employed in photographicapplications.

Upon triggering of the master fiashtube 38 its anode-to-cathode voltageis reduced from substantially the full voltage of the condenser 33 to avalue just sufficient to maintain discharge, thus suddenly impressingthe greater part .of the voltage of condenser 33 across the primarywinding 36 of the saturable core transformer 35. Accordingly, asdescribed in the operation of the saturable core transformer I] of Fig.l, a trig.- gering voltage pulse appears across the secondary winding3". of the transformer l1 whose :magnitude bears the same ratio to theprimary voltage as the turns ratio of the transformer. A second or slavefiashtube 4! is connected to the energizing circuit with its cathode 48connected to the negative plate of thecondenser 33 and its anode 43connected to the end of the secondary winding 41. As previouslydescribed with respect to Fig. l the triggering electrode 58 of theslave fiashtube .41 is connected to the anode .49 through a seriesresistor 5|, the resistor serving to prevent the possibility ofsustained arcing be tween the cathode and triggering electrode. Afterthe core of the transformer 36 saturates, the primary and secondarwindings present a relatively small impedance to current flowtherethrough so that a large conductive current flows through flashtubes38 and 417 from the charged condenser 33. Since it is desired that :bothflash.- tubes carry a substantial portion of the discharged current, nocurrent limiting .orresetting circuit elements corresponding to thecondenser l4 and. the resistor 55 in Fig. 1 are employed in series withthe master flashtube ,33. Flashtubes 3? and 43 may have the sameoperating charace teristics, in which case it is expedient that theprimary and secondary windings of the transformer 36 have the sameresistance, thus assuring an equal division of current throu h thefiashtubes. The division of the current between the fiashtubes may beadjusted in anyothermanner as desired by an well-know-n means.

Since the triggering excitation for the slave fiashtube i? is derivedfrom the discharge =circuit of the master flashtube 38, no additionalload is placed on the master flashtube triggering cir cuit, andaccordingly more than one slave flashtube may be readily employed. Inview of the low triggering energy required for simuitaneously flashing aplurality of fiashtubes, long operating life can be obtained fromrelatively light switch contacts, such as may be conveniently employedin a camera shutter mechanism.

In the modification of my invention illustrated by Fig. 3 a saturablereactor is employed for 7 triggering a plurality of flashtubes, theflashtu-bes suitably being of the type having a cathode and anode as themain electrodes, and a triggering electrode designed to render the tubeconductive when a voltage impulse is applied between the triggeringelectrode and one of the main electrodes. As shown in the figure,terminals 52 and 53 of the charging circuit are connected respectivelyto the negative and positive terminals of a D.-C. voltage source, and acondenser 54, shown with its positively charged plate grounded, isconnected to the terminals. A master fiashtube 55 has its mainelectrodes connected across the condenser 54 with the winding of asaturable reactor 55 connected in series between the flashtube cathodeand negatively charged plate of condenser 54. The reactor may suitablycomprise a substantially closed thinly-laminated ferromagnetic core witha coil consisting of a few turns of heavy copper wire or ribbon, thereactor being arranged to saturate within a few microseconds after adirect current voltage is impressed across it. A second or slavefiashtube i is connected with its main electrodes paralleling thecorresponding electrodes of the master fiashtube 55.

A suitable triggering circuit 58 for initiating the discharge in themaster fiashtube 55, similar to that provided in the embodiment of myinvention illustrated by Fig. 2, is employed.

When the flashtube 55 begins to conduct, substantially all of thevoltage of the condenser 54 is impressed across the terminals of thesaturable reactor 55. In view of the relatively steep wave front of thevoltage thus impressed, the sudden drop of voltage across the mainelectrodes of the master flashtube 55 is readily utilized in triggeringthe slave fiashtube 51. Accordingly, a triggering condenser 59 and theprimary winding of a triggerin transformer 60 are connected in seriesacross the slave fiasht'ube cathode and anode terminals. The condenserand transformer winding act as a differentiating circuit, and the steepwave front of the voltage drop acros the flashtube 55 appears as asharply peaked voltage impulse across the primary winding of thetriggering transformer 60. Accordingly, a corresponding voltage pulseappears across the secondary of the trigger transformer, multiplied bythe turns ratio thereof. Since the trigger transformer secondary windingis connected between the trigger electrode and anode of the slaveflashtube 51, a discharge is thus initiated between its main electrodesin response to the discharge between the main electrodes of the masterflashtube 55.

Inasmuch as the core of the saturable reactor 56 saturates after theflow of current through its winding, the voltage drops sharply a fewmicroseconds after the voltage of condenser 54 is impressed across it.Accordingly, as described previously, with respect to Fig. 2, a largedischarge current from the condenser 54 flows through the saturablereactor 53 and is divided between the master and slave flashtubes 55 and5'! respectively, rendering both luminescent.

As in the embodiment described in Fig. 2, it is obvious that, withoutdeparting from the spirit of my invention, more than one slave tube maybe utilized. In a physical arrangement of the slave tube 51 with respectto the master tube 55, it is desirable, of course, that the circuitconnections between the slave tube triggering transformer 65 and theslave tube 5'! be relatively short, although the other conductors may beof the triggering pulse.

a substantial length without impairing the operation of the slavecircuit. It is to be noted that no secondary winding on the saturablereactor 51 is utilized as in the saturable core inductance devicesemployed in the embodiment shown in Figs. 1 and 2.

Referring to Fig. 4, a flashtube energizing and triggering circuit 51 isprovided for a master flashtube 52 similar to the master fiashtube circuit shown in Fig. 2, but the discharge energy for a slave flashtube 63is provided by a separate D.-C. voltage source; A slave tube triggeringcondenser 64 and a triggering transformer 55 are connected in seriesbetween the anode and cathode of the master flashtube 82 for triggeringthe slave fiashtube 63 in a manner previously described. Onesatisfactory physical arrangement of the slave tube triggeringcomponents is suggested by Fig. l in that the triggering condenser 54may be physically positioned near the master fiashtube assembly so thatthe relatively long leads from the other plate of the triggeringcondenser and the anode of the master fiashtube 62 need have nopotential between them except These leads preferably an tend as acoaxial cable to the primary winding terminals of the slave tubetriggering transformer 65. A separate energizing circuit 66 for theslave fiashtube 63 eliminates the need for conductors other than fortriggering between master and slave fiashtubes. A surge-limitingresistor 5? is shown in dotted outline between the cable conductors nearthe master fiashtube unit junction and may be used to preventdangerously high potentials at the cable terminals when the slave unitis disconnected.

In the modification of my invention shown in Fig. 5, a flashtuoe istriggered in response to a relatively weak signal, such as provided bythe operation of a photo tube. Again input termi nals 63 and 69 of theflashtube energizing circuit are arranged to be connected to thenegative and positive terminals, respectively, of a direct currentvoltage source. A condenser it is connected across the input terminalsso that it may be suitably charged to provide a discharge currentbetween the main electrodes of a flashtube H. A saturable reactor 72 isconnected in series between the negatively charged plate of thecondenser l0 and the cathode of the fiasl1- tube H, and the dischargecircuit is completed by connecting the positively charged plate of thecondenser it to the fiashtube anode.

A gaseous discharge device 13, such as a thyratron which may betriggered by a sufficiently positive signal applied to its grid orcontrol electrode, is connected in parallel with the fiashtube ll,through a current limiting and resetting circuit comprising a condenser14 shunted by a resistor 15. Substantially the full voltage of thecondenser lfi is impressed across the saturable reactor 12 when thethyratron I3 is rendered conductive, and a differentiating circuitcomprising a condenser 15 and the primary winding of a triggeringtransformer ll, is connected in the manner previously described withrespect to Fig. 3, to provide a positive triggering impulse in thesecondary winding of the triggering transformer T1. Since the secondarywinding is connected between the triggering electrode and anode of theflashtube H, the flashtube is rendered conductive upon the firing of thethyratron 13.

To provide a control voltage for triggering the thyratron l3, 9. pair ofvoltage divider resistors 18 and 19 are connected in series across thecon- '9 'd'enser 10. -Aiphoto'tubeiilfl is employed as 1 acircuitclosing means and is connected in series with a "dropping resistor 81havinga very'high ohmic value, the iphototube anddroppingresistor beingshunted around-the voltage divider resistor 19 to place a potentialacross the phototube. The phototube cathode is coupled to the grid ofthe thyratron 13 through a condenser 82 which transmits a positivetriggering pulse to the grid when the phototube is suddenly renderedconductive'and its cathodethereby made more positive.Conventional-negative bias is provided for thethyratron 13 by agrid-biasingreSiStr 83 connected between-the thyratron grid and theoathode of the flashtube 1|,anda resistor 8 connectedbetween thethyratron'cathode and flashtube anode. This modification of my inventionas shown in Fig. 5, has a special utility as an independent slaveflashtube unit in that the photo- .tube .80 may be arranged to conductin response tothe-light flash-from airemote master fiashtube.

'In-each-of the modifications described, I have utilized the peculiarnon-linearcharacteristic of asaturable reactor so that a high impedanceis presented to'asteep wave front of a suddenly impressed voltage forproviding a triggering pulse and a relatively low reactor impedance ispresented after saturation of the core to permit a substantial dischargecurrent through the series circuit. It will be understood that numerousmodifications vmay'besmade by those skilled in the art withoutactuallydeparting from the invention. .I, therefore, aim in the appendedclaims to cover all such equivalent variations as come within the .truespirit and scope of the foregoing disclosure.

What I claim as new and desire to secure by Letters Patent is:

-1. In combination, a condenser, means for charging said condenser, aspace discharge tube possessing an anode, cathode and triggeringelectrode, nieansincluding an impedance connecting said triggeringelectro'de'to said anode, a Winding possessing a saturable .core, meansconnecting said discharge tube from cathode to anode across saidcondenser in series with said winding, and ineansfor inducing avoltagepulse in said winding in additive polarity with respect to thecharge on said condenser for triggering said discharge tube.

2. In combination, a condenser, means for charging said condenser, aspace discharge tube possessing electrodes including an anode and acathode, a winding possessing a saturable core, means connecting saiddischarge tube from cathode toano'de across saidcondenser in serieswithsaid winding, means'for inducing a voltage 'pul'sein said winding inadditive polarity with respect'tothecharge on said condenser fortriggerings'aid dischargetube.

3. In "combination, a condenser, means for charging saidcondenser, asaturable core transformer possessing 19, primary and a secondarywinding, first circuit means including a switch adapted to cause a shortcurrent pulse through the primary of said transformer upon actuation ofsaid switch, a space discharge tube possessing electrcdesdncluding ananodeand acathodasecond circuit means adapted to connect said dischargetube across said condenser and the secondary winding of said transformerin series thereby utilizing the transient voltage in said secondarywinding caused by a short current pulse in said primary to trigger saidspace discharge tube andeallowingsdischarge of said condenser throughsaid discharge tube.

'10 4. In combination, D.-C. energy storing means, means for supplyingenergy intermittently to said storing means, a saturable coretransformer having at least two windings, normally open switching means,circuit means connecting one winding of said transformer and saidswitching means in series across said energy storing means, means foractuating said switchin means to closed condition, automatic resettingmeans responsive to integrated current-flow through said switching meansfor returning said switching means to normal open condition, a coldcathode space discharge tube possessing electrodes includinga cathodeand an anode, and means connecting a second winding of said transformerand said space discharge tube in series across said energy storingmeans.

5.111 combination, an electrical condenser, means for intermittentlycharging said condenser, a saturable core transformer possessing atleast two windings, a thermionic gaseous discharge tube possessing acathode, anode, and control grid, means oonnectingsaid condenser, awindingof'said transformer and said gaseous discharge tube in seriesrelationship, means controlling'the grid of said-gaseous discharge tube,

automatic resetting means responsive to the integrated current flowthrough said gaseous discharge tube for causing said tube to-becomenonconducting, acold cathode space discharge tube possessing electrodesincluding a cathode 1 and an anode, and means connecting a secondWinding of said transformer and said cold cathodedischarge tube inseries acrosssaid-condenser.

6. An energizing-circuit fora flashtube comprising a- D.-C. voltagesource connected-tosustain a flow of current through the fiashtube, asaturable core transformer having its secondary series connected inthecircuit between the flashtube and said source, and meansto apply avoltage impulse to the primary of said transformer of proper polarity toinduce a voltage in the secondary having a polarityadditive to that ofsaid source.

7. An energizing circuit for a, flashtube comprisingacapacitor-connected between the oathode and anode of the flashtube, asaturable core transformer having its secondary series connected in thecircuit between the flashtube and said capacitor, means for chargingsaid capacitor to a -D.-C. voltage sufiicient to sustainbut nottoinitiate current through the fiashtube, and means toapply a Voltageimpulse to the primary of said transformer of proper polarity to inducea voltagein the secondaryhaving a polarity additive to that of thecapacitor voltage.

-8. An energizing circuit for a flashtube comprising a capacitor,circuit means for connecting said capacitor between the cathode andanode of the flashtube, a saturable core transformer havingits-secondary series connected in the circuit between the fiashtube andsaid capacitor, means-for charging said capacitor to a D.-C. voltagesufiicient to sustain but not to initiate current through the'flashtube, and switching means adapted upon actuation tosuddenlyconnect the primary of said transformer across said capacitor,the relative polarities of the transformer primary and secondary beingsuch that upon actuation of theswitchingmeansa voltage is induced in thesecondary having a polarity additive to that of thecapacitor voltage.

9. An energizing circuit fora :flashtube comprising a capacitorconnected between the oathode fiand anode of the flashtubaa saturablecore transformer having its secondary series connected in the circuitbetween the fiashtube anode and said capacitor, means for charging saidcapacitor to a D.-C. voltage sufiicient to sustain but not to initiatecurrent through the flashtube, and switching means adapted uponactuation to suddenly connect the primary of said transformer acrosssaid capacitor, the relative polarities of the transformer primary andsecondary being such that upon actuation of the switching means avoltage is induced in the secondary having a polarity additive to thatof the capacitor voltage.

10. An energizing circuit for a fiashtube comprising a capacitorconnected between the oathode and anode of the fiashtube, a saturablecore transformer having its secondary series connected in the circuitbetween the fiashtube and said capacitor, means for charging saidcapacitor to a D.-C. voltage sufiicient to sustain but not to initiatecurrent through the flashtube, a normally non-conducting grid-controlleddischarge tube connected in series with the primary of said transformeracross said capacitor, and means to apply a triggering voltage to thegrid of said discharge tube to make such tube conductive, the relativepolarities of the transformer primary and secondary being such that uponthe discharge tube becoming conductive a voltage is induced in thesecondary having a polarity additive to that of the capacitor voltage.

11. In a fiashtube energizing circuit, apparatus for producing atriggering impulse comprising a first capacitor, means for charging saidfirst capacitor, a transformer, a second capacitor, a normallynon-conductive grid-controlled discharge tube, said first capacitor, theprimary of said transformer, said second capacitor, and said dischargetube being series connected in a closed circuit loop, a resistorconnected in parallel with said second capacitor, and means to apply atriggering voltage to the grid of said discharge tube to make such tubeconductive.

12. An energizing circuit for a flashtube comprising a first capacitorconnected between the cathode and anode of the flashtube, a saturablecore transformer having its secondary series connected in the circuitbetween the fiashtube and said capacitor, means for charging said firstcapacitor to a D.-C. voltage sufficient to sustain but not to initiatecurrent through the fiashtube, a second capacitor, a normallynon-conductive grid-controlled discharge tube, said second capacitor andthe primary of said transformer being connected in series in the ordernamed between the anode of said discharge tube and one plate of saidfirst capacitor, the other plate of said first capacitor being connectedto the cathode of said discharge tube, a resistor connected in parallelwith said second capacitor, and means to apply a triggering voltage tothe grid of said discharge tube to make such tube conductive, therelative polarities of the transformer primary and secondary being suchthat upon the discharge tube becoming conductive a voltage is induced inthe secondary having a polarity additive to that of the first capacitorvoltage.

13. In combination, a flashtube having a cathode, anode, and triggeringelectrode, a resistor connecting the fiashtube anode and triggeringelectrode, a first capacitor having one of its plates connected to thefiashtube cathode, a saturable core transformer having its secondaryconnected between the other plate of said first capacitor and thefiashtube anode, means for charging said first capacitor to a D.-C.voltage sufficient to sustain but not to initiate current through theflashtube, a second capacitor, a normally nonconductive grid-controlleddischarge tube, said second capacitor and the primary of saidtransformer being connected in series in the order named between theanode of said discharge tube and one plate of said first capacitor, theother plate of said first capacitor being connected to the cathode ofsaid discharge tube, a first resistor connected in parallel with saidsecond capacitor, a second resistor connecting the grid and cathode ofsaid discharge tube, a source of negative voltage relative to thedischarge tube cathode, a third capacitor connected between said sourceof negative voltage and the discharge tube grid, and switching meansadapted upon actuation to suddenly short out the negative voltageapplied to said third capacitor, So that the grid of the discharge tubeis driven positive and the tube becomes conductive, the relativepolarities of the transformer primary and secondary being such that uponthe discharge tube becoming conductive a voltage is induced in thesecondary having a polarity additive to that of the first capacitorvoltage.

14. in combination, a fiashtube having a cathode, anode, and triggeringelectrode, a resistor connecting the fiashtube anode and triggeringelectrode, a first capacitor having its first plate connected to thefiashtube cathode, a saturable core transformer having its secondaryconnected between the second plate of said first capacitor and thefiashtube anode, a first voltage source connected to charge the firstcapacitor with its first plate positive relative to its second plate,secon capacitor, a normally non-conductive controlled discharge tube,said second capacitor and the primary of said transformer beingconnected in series in the order named between the anode of saiddischarge tube and the first plate of the first capacitor, the cathodeof said discharge tube being connected to the second plate of the firstcapacitor, a first resistor connected in parallel with said secondcapacitor, a second resistor connecting the grid and cathode of saiddischarge tube, a second voltage source adapted to supply a voltagenegative with respect to the cathode of said discharge tube, a thirdresistor and a third capacitor connected in series in the order namedbetween the second voltage source and the grid of said discharge tube,and switchng means adapted upon actuation to suddenly establish a shortcircuit connection between the plate of the third capacitor connected tothe third resistor and the cathode of the discharge tube, so that thegrid of the discharge tube is driven positive and the tube becomesconductive, the relative polarities of the transformer primary andsecondary being such that upon the discharge tube becoming conductive avoltage is induced in the secondary having a polarity additive to thatof the first capacitor voltage.

15. An electric circuit comprising a saturable core inductance deviceand a switch connected in series, means for applying a voltage acrosssaid series-connected inductance device and switch in order to impressan impulse voltage across said inductance device when said switch isclosed, a gaseous discharge device having electrodes including a pair ofmain electrodes, means for applying a voltage between said pair of mainelectrodes, and means responsive to said impulse voltage for renderingsaid discharge device conductive.

16. An electric circuit comprising a saturable core inductance deviceand a first gaseous discharge device connected in series, means forapplying a unidirectional voltage across said seriesconnected inductancedevice and first discharge device, means for rendering said firstdischarge device conductive to impress an impulse voltage across saidinductance device, a second gaseous discharge device having a pair ofmain electrodes, means for applying a unidirectional voltage across saidpair of main electrodes, and means responsive to said impulse voltage torender said discharge device conductive.

17. An electric circuit comprising a saturable core inductance device, afirst gaseous discharge device, an energy storage means, circuit meansfor connecting said inductance device and said first discharge device inseries across said energy storage means, means for charging said energystorage means to a D.-C. voltage sufficient to sustain but not toinitiate current through said first discharge device, means forrendering said fi st discharge device conductive to apply an impulsevoltage across said inductance device, a second gaseous discharge devicehaving a pair of main electrodes, means for applying a voltage acrosssaid pair of main electrodes, and means responsive to said impulsevoltage for rendering said second discharge device conductive.

18. In a fiashtube circuit, a triggering circuit comprising a saturablecore inductance device and a switch connected in series, means forapplying a unidirectional voltage across said seriesconnec tedinductance device and said switch in order to impress an impulse voltageacross said inductance device upon the closing of said switch, and meansresponsive to said impulse voltage for rendering said flashtubeconductive.

19. An energizing circuit for a plurality of gaseous discharge deviceseach having a pair of main electrodes which comprises a saturable coreinductance device, a circuit means for connecting said inductance deviceand the main electrode of one of said gaseous discharge devices inseries, means for applying a unidirectional voltage across saidseries-connected inductance device and first discharge device, means forrendering said one of said discharge devices conductive to apply animpulse voltage across said inductance device, and means responsive tosaid impulse voltage for rendering another of said discharge devicesconductive when its main electrodes are connected to a voltage source.

An energizing circuit for a flashtube comprising a capacitor, asaturable core inductance device connecting one terminal of saidcapacitor to the a of said fiashtube, a gaseous discharge device, saiddischarge device being connected to said capacitor through saidinductance device, means to trigger said discharge device to cause apulse of voltage in said inductance device, said flashtuce beingarranged for triggering in response to such voltage pulses, saidinductance device core being saturated by the induction current of saidfiashtube and discharge device whereby substantially the full voltage ofsaid capacitor is applied to said fiashtube to maintain conductiontherein.

21. In combination, an energy storage means, means for charging saidstorage means, a saturaile core inductance device, a gaseous dischargedevice, circuit means for connecting said inductance device and saidfirst discharge device in series across said energy storage means, meansfor rendering said first discharge device conductive to impress animpulse voltage across said inductance device, a second gaseousdischarge device connected across said energy storage means in serieswith said inductance device, and means responsive to said impulsevoltage for rendering said second discharge device conductive.

22. In combination, a plurality of gaseous discharge devices, a directcurrent voltage source connected to said discharge devices, a saturablecore inductance device connected in series between said dischargedevices and said voltage source, means for rendering one or saiddischarge devices conductive to suddenly apply a voltage cross saidinductance device, and means responsive to said sudden voltageapplication to initiate current flow through another of said dischargedevices, at least one of said discharge devices being arranged to emitlight upon the passage of current therethrough.

23. An energizing circuit for a plurality of gaseous discharge devicescomprising an energy storage means, means for charging said storagemeans, a saturable core inductance device, means for connecting saidinductance device and one of said discharge devices in series acrosssaid energy storage means, means for rendering said one of saiddischarge devices conductive to switch an impulse voltage across saidinductance device, means for connecting said inductance device andanother of said discharge devices in series across said energy storagemeans, and means responsive to said impulse voltage for rendering saidanother of said discharge devices conductive, at least one of saiddischarge devices being arranged to emit light upon the passage ofcurrent therethrough.

24. A flashtube energizing circuit comprising a first gaseous dischargedevice, a capacitor, means for charging said capacitor, said capacitorbeing connected to sustain a flow current through said first dischargedevice when sai-c device is rendered conductive, a saturable coreinductance device serially connected between said first discharge deviceand said capacitor, means for triggering said first discharge device forsuddenly impressing at least part of the voltage of said source acrosssaid inductance device, and means responsive to said impressing of saidvoltage to trigger a second gaseous discharge device, at least one ofsaid discharge devices being arranged to emit light upon the passage ofcurrent therethrough.

25. An energizing circuit for a fiashtube comprising a unidirectionalvoltage source connected to sustain a flow of current through thefiashtube, a saturable core inductance device serially connected betweensaid fiashtube and said source, a gaseous discharge device, saiddischarge device being connected to said voltage source through saidinductance device, means for rendering said discharge device conductiveto establish a sudden change of voltage across said inductance devicebefore saturation thereof, means for rendering said fiashtube conductivein response to said sudden change of voltage, said inductance devicebeing saturated, by the conduction current of said fiashtube and saiddischarge device therethrough whereby substantially the full voltage ofsaid source is applied to said discharge device and said flashtube.

26. An energizing circuit for a plurality of fiashtubes comprising aunidirectional voltage source connected to sustain a fiow of currentthrough said fiashtubes, a saturable core transformer having its primarywinding serially connected in circuit between a first or said pluralityof fiashtubes and said source and having its secondary windingserially'connected in circuit be tween a second of said fiashtubes andsaid source,

means for rendering said first of said flashtubes conductive to therebyapply a voltage impulse to the primary winding of said transformer ofproper plurality to induce a voltage in the secondary winding having apolarity additive to said source.

27. An energizing circuit for a plurality of fiashtubes comprising acondenser, means for charging said condenser to a voltage sufficient tosustain a fiow of current through said fiashtubes, a saturable coretransformer having its primary winding serially connected in circuitbetween a first of said flashtubes and said source and a secondarywinding serially connected circuit between a second of said flashtubesand said source, and means for rendering said first of said fiashtubesconductive to thereby apply a voltage impulse to the primary winding ofsaid transformer of proper polarity to induce a voltage in the secondarywinding having a polarity additive to said source.

28. In combination, an energy storing means, means for supplying energyto said storing means, a saturable core transformer having at least twowindings, a first gaseous discharge device, circuit means connecting onewinding of said transformer and said first gaseous discharge device inseries across said energy storing means, a second gaseous dischargedevice, circuit means connecting a second winding of said transformerand said second discharge device in series across said energy storingmeans, and means for rendering said fi t gaseous discharge deviceconductive to thereby apply a voltage impulse to the primary winding ofsaid transformer of proper polarity to induce a voltage in the secondarywinding havin a polarity additive to said source.

29. In a flashtube energizing circuit, apparatus for producing atriggering impulse in the secondary winding of a triggering transformercomprising a first capacitor, means for charging said first capacitor, asaturable reactor, a normally non-conductive grid-controlled dischargedevice, said first capacitor, said reactor, and said discharge devicebeing serially connected in a closed circuit loop, means for applying atriggering voltage to the grid of said discharge device to render saiddischarge device conductive, and a differentiating circuit comprising aserially connected second capacitor and the primary winding of saidtriggering transformer connected in parallel with said discharge device.

30. An energizing circuit for a plurality of fiashtubes comprising anenergy storage means connected to sustain a flow of current through saidflashtubes, means for charging said storage means, a saturable reactorserially connected between said fiashtubes and said storage means, meansfor rendering one of said fiashtubes conductive to cause a sudden changeof voltage across said reactor before saturation thereof, means forrendering another of said fiashtubes conductive in response to saidsudden change of voltage, said inductance device core being saturated byconduction of current of said flashtubes whereby substantially the fullvoltage of said source is applied to said flashtubes to cause saidfiashtubes to become luminescent by the passage of current therethrough.

31. An energizing circuit for a plurality of gaseous discharge devicescomprising a unidirectional voltage source connected to sustain a flowof current through said fiashtubes, a saturable core inductance deviceserially connected between said gaseous discharge devices and saidsource, means for rendering one of said discharge devices conductive toestablish a sudden change of voltage across said inductance devicebefore saturation thereof, and triggering means for rendering another ofsaid discharge devices conductive in response to said sudden change ofvoltage, said triggering means comprising a capacitor and a transformerhaving two windings, said capacitor and one of said windings beingconnected in series across said one of said discharge devices, and theother of said windings being connected between a control electrode andmain electrode of said another of said discharge devices, saidinductance device being saturated by the conduction current of saidfiashtubes whereby substantially the full voltage of said source isapplied to said discharge devices.

32. An energizing circuit for a plurality of fiashtubes comprising afirst capacitor, means for charging said first capacitor, a saturablecore reactor, circuit means for connecting said reactor and one of saidplurality of fiashtubes in series across said first capacitor, means forrendering said one flashtube conductive to impress an impulse voltageacross said reactor, and triggering means responsive to said impulsevoltage for rendering another of said flashtubes conductive, saidtriggering means comprising a second capacitor, a transformer, circuitmeans for connecting said second capacitor and the primary winding ofsaid transformer across said one flashtube, and circuit means connectingthe secondary winding of said transformer to said another of saidfiashtubes.

33. An energizing circuit for a plurality of fiashtubes each having apair of main electrodes and a triggering electrode, which comprises afirst capacitor, means for charging said first capacitor, a saturablereactor, circuit means for connecting the main electrodes of at leastone of said plurality of fiashtubes across said first capacitor throughsaid reactor, means for triggering said one fiashtube to thereby impressan impulse voltage across said reactor, and triggering means responsiveto said impulse voltage for rendering another of said fiashtubesconductive, said triggering means comprising a second capacitor, atransformer having a primary and secondary winding, circuit means forconnecting said second capacitor and the primary winding of saidtransformer across said one flashtube, and circuit means connecting thesecondary winding of said transformer between one of the main electrodesand the triggering electrode of said another of said flashtubes.

34. An energizing circuit for a plurality of flashtubes comprising afirst capacitor, means for charging said first capacitor, a saturablecore reactor, circuit means for connecting each of said plurality offlashtubes across said first capacitor in series with said reactor,means for rendering said one of said plurality of fiashtubes conductiveto impress an impulse voltage across said reactor device, and triggeringmeans responsive to said impulse voltage connected to render another ofsaid flashtubes conductive, said triggering means comprising a secondcapacitor and a transformer with circuit means for connecting saidsecond capacitor and a winding of said transformer across said onefiashtube.

HAROLD W. LORD.

No references cited.

